1. Field of the Invention
The present invention relates to a film deposition apparatus, a substrate processor, a film deposition method, and a computer-readable storage medium storing a program for causing a computer to execute the film deposition method.
2. Description of the Related Art
Processes such as those called atomic layer deposition (ALD) and molecular layer deposition (MLD) are known as film deposition techniques in the semiconductor manufacturing process. According to these processes, a first reaction gas is adsorbed on the surface of a semiconductor wafer (hereinafter referred to as “wafer”), serving as a substrate, in a vacuum atmosphere, and thereafter, the fed gas is switched to a second reaction gas, thereby forming a single or multiple atomic or molecular layers through reaction of the first and second reaction gases. This cycle is repeated one or more times, and a film is deposited on the substrate by stacking these layers. According to these processes, it is possible to control film thickness with high accuracy based on the number of cycles, and the deposited film has excellent uniformity in in-plane quality. Thus, these processes are effective techniques that can address reduction in the film thickness of semiconductor devices.
For example, such a film deposition method is suitable for depositing a high-k dielectric film used for a gate oxide film. By way of example, in the case of depositing a silicon oxide film (SiO2 film), gas such as bis(tertiary-butylamino) silane (BTBAS) gas is used as a first reaction gas (source gas), and gas such as ozone gas is used as a second reaction gas (oxidation gas).
In order to carry out such a film deposition method, studies have been made of a method that employs a single-wafer film deposition apparatus having a shower head at the top center part of a vacuum chamber to feed reaction gases from above the center part of a substrate and to discharge unreacted reaction gases and reaction by-products from the bottom of the chamber. According to this film deposition method, it takes a long time for a purge gas to complete gas replacement, and the number of cycles reaches, for example, several hundred, thus resulting in the problem of a long process time. Therefore, there is a demand for apparatuses and techniques that can perform processing with high throughput.
In view of this, apparatuses that perform a film deposition process with multiple substrates arranged on a turntable in its rotation direction in a vacuum chamber have been known as follows.
Patent Document 1 listed below describes a configuration where a flat cylindrical vacuum chamber is divided into right and left semicylindrical regions having respective evacuation ports formed along semicircular outlines so as to perform evacuation in an upward direction. An ejection port for a separation gas is formed between the right and left semicylindrical regions along a diameter of the vacuum chamber. The right and left semicylindrical regions have respective feed regions for feeding source gases different from each other. A turntable inside the vacuum chamber rotates so that workpieces pass the right semicylindrical region, the dividing region, and the left semicylindrical region, and the source gases are evacuated from the corresponding evacuation ports.
Patent Document 2 listed below describes a configuration where four wafers are arranged at equal intervals on a wafer support member (turntable) along its rotation direction while first reaction gas ejection nozzles and second reaction gas ejection nozzles are disposed at equal intervals along the rotation direction so as to be opposed to the wafer support member with purge nozzles placed between them; and the wafer support member is caused to rotate horizontally. Each wafer is supported by the wafer support member, so that the surface of the wafer is positioned higher than the upper surface of the wafer support member by the thickness of the wafer. Further, Patent Document 2 also discloses that the nozzles are provided to extend in a radial direction of the wafer support member so that there is a distance of 0.1 mm or more between the wafers and the nozzles. Vacuum evacuation is performed through the space between the periphery of the wafer support member and the inner wall of a process chamber. According to this apparatus, the space below the purge nozzles serves as a so-called air curtain so as to prevent the first reaction gas and the second reaction gas from mixing.
Patent Document 3 listed below describes a configuration where a vacuum chamber is divided circumferentially into multiple process chambers by partition walls and a circular placement table rotatable through thin gaps below the lower ends of the partition walls is provided so that multiple wafers are placed on the placement table.
Patent Document 4 listed below describes the technique of partitioning a circular gas feed plate circumferentially into eight portions, arranging AsH3 gas feed ports, H2 gas feed ports, TMG gas feed ports, and H2 gas feed ports 90 degrees apart, providing evacuation ports between these gas feed ports, and rotating a susceptor supporting wafers and opposed to the gas feed plate.
Patent Document 5 listed below describes a configuration where the region on a turntable is partitioned crisscross into four placement regions by four vertical walls so as to place wafers in the four placement regions, source gas (reaction gas) injectors and purge gas injectors are arranged alternately in a rotation direction to form a cross-shaped injector unit, and the injector unit is caused to rotate horizontally so as to position each of these injectors in the four placement regions in order while performing evacuation from the periphery of the turntable.
Further, Patent Document 6 listed below (corresponding to Patent Documents 7 an 8) describes an apparatus that causes a susceptor having wafers placed thereon to rotate and feeds source and purge gases from above the susceptor in performing atomic layer CVD that causes multiple gases to be adsorbed alternately on a target (corresponding to a wafer). Patent Document 6 discloses at paragraphs [0023] through [0025] that partition walls extend radially from the center of a chamber with gas outlet holes for feeding a reaction gas or a purge gas to a susceptor provided at the bottom of the partition walls and that a gas curtain is formed by letting out an inert gas from gas outlet holes of the partition walls. Evacuation is described at paragraph [0058]. According to this description, a source gas and a purge gas are evacuated separately through respective evacuation channels.                Patent Document 1: U.S. Pat. No. 7,153,542 (FIGS. 6A and 6B)        Patent Document 2: Japanese Laid-Open Patent Application No. 2001-254181 (FIGS. 1 and 2)        Patent Document 3: Japanese Laid-Open Patent Application No. 3,144,664 (FIGS. 1 and 2 and claim 1)        Patent Document 4: Japanese Laid-Open Patent Application No. H4-287912        Patent Document 5: U.S. Pat. No. 6,634,314        Patent Document 6: Japanese Laid-Open Patent Application No. 2007-247066 (paragraphs 0023 through 0025 and 0058, and FIGS. 12 and 18)        Patent Document 7: United States Patent Application Publication No. 2007/0218701        Patent Document 8: United States Patent Application Publication No. 2007/0218702        